Mixed Outcomes for Radiosurgery in Brain Tumors

According to two reviews published in the International Journal of Radiation Oncology, Biology, Physics, radiosurgery results in better outcomes for some, but not all, brain tumors.

Stereotactic radiosurgery involves the delivery of radiation to a very precise location in the brain, thus limiting damage to surrounding normal tissue. It does not involve actual surgery. Stereotactic radiosurgery may be used alone or it may be used in combination with other types of radiation therapy or chemotherapy.

In order to summarize the available scientific evidence about the effectiveness of radiosurgery for treatment of two types of brain tumors in adults (brain metastases and malignant glioma), researchers with the American Society for Therapeutic Radiation and Oncology (ASTRO) reviewed published studies.

Brain metastases are cancers that have spread to the brain from another part of the body. They most commonly result from cancers of the lung, breast, and colon, and melanoma. Brain metastases are more common than cancer that originates in the brain.

Based on review of the scientific evidence, the ASTRO researchers concluded that for some patients with small brain metastases, adding radiosurgery to whole-brain radiation therapy reduces the likelihood of recurrence or progression compared to whole-brain radiation therapy alone. It was also noted that there is a small increase in toxicity with the addition of radiosurgery. While the use of radiosurgery alone (without whole-brain radiation) for initial treatment of brain metastases does not appear to alter survival, it may increase the risk of recurrence or progression. There is little information about the effect of radiosurgery for management of brain metastases that have recurred or progressed.

Malignant glioma refers to a group of cancers that develop in glial cells, which are the most abundant cells of the nervous system. These cells provide many supportive functions that facilitate the work of the neurons (cells that transmit impulses between the brain, spinal column, and nerves). There are several types of malignant glioma, including anaplastic astrocytoma, anaplastic oligodendroglioma, anaplastic mixed oligoastrocytoma, and glioblastoma multiforme.

For treatment of glioma, the ASTRO researchers found little evidence of a benefit from radiosurgery. Adding radiosurgery to treatment with external beam radiation and the chemotherapy drug carmustine does not appear to improve survival compared to treatment with external beam radiation and carmustine alone, but it does increase treatment toxicity. There is little information about the use of radiosurgery for managing glioma recurrence or progression.

Based on these reviews, it appears likely that the risks and benefits of radiosurgery for brain tumors will vary by type of tumor and other treatments given. Additional studies are necessary to clarify remaining questions about which patient populations are most likely to benefit from radiosurgery.

References:

Mehta MP, Tsao MN, Whelan TJ et al. The American Society for Therapeutic Radiology and Oncology (ASTRO) evidence-based review of the role of radiosurgery for brain metastases. International Journal of Radiation Oncology, Biology, Physics. 2005;63:37-46.

Tsao MN, Mehta MP, Whelan TJ et al. The American Society for Therapeutic Radiology and Oncology (ASTRO) evidence-based review of the role of radiosurgery for malignant glioma. International Journal of Radiation Oncology, Biology, Physics. 2005;63:47-55.